Indigosol composition comprising a naphthol sulfonate and method of applying same



Patented July 20, 1948 INDIGOSOL COMPOSITION COMPRISING A NAPHTHOL APPLYING SAME SULFONATE AND METHOD OF Earl L. Pelton and Charles 0. 'Hutchem'euther, Midland, Mich., assignors to The Dow Chemical C pany, Delaware Midland, Mich-., a corporation of No Drawing. Application October 5, 1945, Serial No. 620,624

Claims. (Cl. -70) This invention concerns certain new compositions comprising, as essential ingredients, an Indigosol derived from tetrabromindigotogether with an agent for facilitating development, 1. e. hydrolysis and oxidation, of the Indigosol to the colored form of tetrabromindigo. It pertains especially to powders and pastes comprising said essential ingredients, which powders and pastes are adapted for use in the dyeing and printing of textile fibers and fabrics. It pertains more particularly to such pastes which, when supplemented by usual Indigosol-printing aids, e. g. an oxidizing agent and a printing gum or other thickener, are adapted for use in fabric printing processes which involve development of the dyestuff on the fabric by steaming of the latter. The invention also concerns a method of printing fabrics and the like with the new compositions and developing the dyestuif color by steaming.

The dyestuffs known as Indigosols, i. e. acidsulphate esters of the leuco form of indigoid dyes, are, when in the form of their alkali salts, sufficiently stable for storage and shipment. They are used extensively for the dyeing and printing of fabrics. Use of the Indigosols permits the dyer to avoid a step of reducing the usual oxidized form of the corresponding indigoid vat dye. Also, the Indigosols may be applied to fabrics in conjunction with other dyestuffs, e. g. azo dyes, to obtain desired color combinations.

After application of an Indigosol to a fabric, the color of the corresponding indigoid vat dye is developed by hydrolysis and oxidation of the Indigosol, usually under acidic conditions and in the presence of an oxidizing agent such as sodium or potassium nitrite, chlorate, or bichromate, etc. Development may be accomplished by immersion in an aqueous bath containing the developing agents, or it may be accomplished by steaming under acidic conditions of a fabric which has been treated with a mixture comprising an Indigosol and an oxidizing agent.

For printing purposes, particularly the printing of fabrics in a continuous manner, development by steaming is most convenient and economical and is preferred when it may satisfactorily be employed. However, Indigosols are known to vary widely as regards the readiness with which they undergo development to the colored form of the corresponding indigoid vat dye, and steaming is less effective than immersion in a developing bath in causing development of the Indigosols which are resistant to hydrolysis and oxidation. Accordingly, although most, if not all, Indigosols may satisfactorily be used in dye- 2 I ing and printing processes wherein development is accomplished by immersion in a bath, certain Indigosols, including those with which this invention is concerned, have not heretofore been adapted for use in processes involving development of the dyestuff by steaming. For instance, Christ, J. Soc. Dyers and Colourists, 54,94 (1938), in a table indicating the relative ease with which various Indigosols undergo development, terms Indigosol 043 (i. e. the sodium acid-sulphate ester of leuco 5,7,5','7'-tetrabromindigo)yinert." In this publication, the Indigosols were presumably developed by steaming, since Indigosol 043 does not develop readily under usual steaming conditions, but is readilydeveloped by immersion in an acidic developing bath. v

We have discovered that an Indigosol derived from tetrabromindigo, e. g. Indigosol 0413, may be caused to develop readily in a steaming operation by admixing one or more of certain naphthol sulphonic acids, or salts thereof, with the Indigosol prior to the steaming operation. The naphthol sulphonic acids which we have found to be effective for the purpose are l-naphthol-Z-sulphori-ic acid, l-naphthol-i-sulphonic acid and Z-naphthol-7-sulphonic acid. A number of other naphthol monoand di-sulphonic acids were similarly tested, but were found to have relatively little, or no, action in accelerating development of the dyestuif. V v

Thecompositions provided by the invention are powders, or pastes, which comprise as essential ingredients a salt of an Indigosol derived from tetrabromindigo, preferably 5,7,5,7'-tetrabromindigo, and a salt of one or more of the abovementioned naphthol sulphonic acids which are effective in promoting development of the dyestuff to its colored form. Usually, a minor amount of an alkali, e. g. sodium or potassium carbonate, is also added further to stabilize'the Indigosol during storage and shipment. The Indigosol and naphthol sulphonic acid are usually employed in the form of alkali salts thereof, e. g. sodium or potassium salts, butother salts such as alkanolamine salts of the compounds may be .used.

The naphthol sulphonate is somewhat effective in'increasing the readiness with which theIndigosol may be developed, regardless of the proportion in which it is used but,'for use in printing operations in which the color is to be developedby steaming, it is advantageously employed in amount corresponding to between 3 and 20 per cent of the weight of the Indigosol. However; it

steps or ingredients stated by any of the following claims or the equivalent of such stated steps or ingredients be employed.

We therefore particularly point out and distinctly claim as our invention:

1. A composition for coloring fabrics, which composition comprises essential ingredients 2. salt of an acid-sulfate ester of a leuco dyestufi derived from tetrabromindigo and a salt of a naphthol sulphonic acid selected from the class consisting of l-naphthol-Z-sulphonic acid, 1- naphtholi-sulphonic acid and Z-naphthol-Y- sulphonic acid.

2. A composition for coloring fabrics, which composition comprises as essential ingredients an alkali metal acid-sulphate ester of the leuco form of 5,7,5',7-tetrabromindigo and an alkali metal salt of a naphthol sulphonic acid selected from the class consisting of l-naphtho1-2-sulphonic acid, l-naphthol-4-sulphonic acid and 2- naphthol-7-sulphonic acid, the naphthol sulphonate being present in amount corresponding to at least 3 per cent of the weight of the alkali metal acid-sulphate ester of leuco 5,7,5',7-tetrabromindigo.

3. A composition for coloring fabrics, which composition comprises as essential ingredients a sodium acid-sulphate ester of the leuco form of 5,7,5,7'-tetrabromindigo and a sodium salt of a naphthol sulphonic acid selected from the class consisting of l-naphthol-Z-sulphonic acid, 1 naphthol-l-sulphonic acid, and 2-naphthol-7- sulphonic acid, the naphthol sulphonate being present in amount corresponding to between 3 and 20 per cent of the weight of the sodium acid sulphate ester of leuco 5,7,5,7'-tetrobr0mindig0.

4. A composition as defined in claim 1, when in the form of a powder.

5. A composition as defined in claim 2, when in the form of a powder.

6. A composition as in the form of a powder.

7. A paste comprising the composition define-d by claim 1 and intimately admixed therewith an aqueous medium and a thickening agent.

8. A paste comprising the composition defined by claim 2 and intimately admixed therewith an aqueous medium and a thickening agent.

9. A paste comprising the composition defined by claim 3 and intimately admixed therewith an aqueous medium and a thickening agent.

10. A printing paste comprising a salt of an acid-sulfate ester of a leuco dyestufi derived from tetrabromindigo, a salt of a naphthol sulphonic acid selected from the class consisting of l-naphthol-2-sulphonic acid, l-naphthol-l-sulphonic acid and 2-naphthol-7-sulphonic acid, an oxidizing agent, an aqueous medium, and a thickening agent.

11. A printing paste which comprises an alkali metal acid-sulphate ester of the leuco form of 5,7,5',7'-tetrabromindigo, an alkali metal salt of a naphthol sulphonic acid selected from the class consisting of l-naphthol-Z-sulphonic acid, 1-

defined in claim 3, when naphthol-i-sulphonic acid, and -naphthol-7- sulphonic acid, an oxidizing agen a printing gum, and an aqueous medium.

'12. A printing paste which comprises an alkali metal acid-sulphate ester of the leuco form of 5,7,5,7'-tetrabromindigo, an alkali metal salt of a naphthol sulphonic acid selected from the class consisting of l-naphthol-Z-sulphonic acid, 1- naphthol-l-sulphonic acid, and 2-naphthol-7- sulphonic acid, an oxidizing agent in amount sufficient to oxidize the dyestufi during development of the latter, a printing gum, and water, the naph thol sulphonate being present in amount corre sponding to at least 3 per cent of the weight of the alkali metal acid sulphate ester of the leuco 5,7,5.,7'-tetrabromindigo.

13. A printing paste which comprises a sodium acid-sulphate ester of the leuco form of 5,7,5','7'- tetrabromindigo, a sodium salt of a naphthol sulphonic acid selected from the class consisting of 1-naphthol-2-sulphonic acid, l-naphthol-4-sulphonic acid, and 2-naphthol-7-sulphonic acid, an oxidizing agent in amount sufiicient to oxidize the dyestufi during development of the latter, a printing gum, and water, the naphthol sulphonate being present in amount corresponding to at least 3 per cent of the weight of the sodium acid sulphate ester of the leuco 5,7,5,7-tetrabromindigo.

1 1. The process which comprises printing a fabric with a printing paste comprising a salt of an acid-sulfate ester of a leuco dyestuif derived from tctrabromindigo and a salt of a naphthol sulphonic acid selected from a class consisting of lnaphthol-2-sulphonic acid, l-naphthol-i-sulphonic acid and 2-naphthol-7-sulphonic acid, the naphthol sulphonate being present in amount corresponding to at least 3 per cent of the weight of the acid-sulfate ester of a leuco dyestuif.

15. The process which comprises printing a fabric with a printing paste comprising an alkali metal acid-sulphate ester of 5,7,5",'7'-tetrabromindigo, an oxidizing agent in amount sufficient to oxidize the dyestuff during the development of the latter, an alkali metal salt of a naphthol sulphonic acid selected from the class consisting of 1-naphtho1-2-sulphonic acid, 1-naphthol-4 sulphonic acid and 2-naphthol-7-sulphonic acid, the naphthol sulphonate being present in amount corresponding to between 3 and 20 per cent of the weight of the alkali metal acid sulphate ester of the leuco 5,7,5',7'-tetrabromindigo and thereafter acidifying and developing the dyestuif on the fabric by exposing the later to steam.

EARL L. PELTON. CHARLES O. HUTCHENREUTHER.

REFERENCES CITED UNITED STATES PATENTS Name Date Chambers Sept. 19, 1939 Number 

